Tellurium compounds useful for deposition of tellurium containing materials

ABSTRACT

Precursors for use in depositing tellurium-containing films on substrates such as wafers or other microelectronic device substrates, as well as associated processes of making and using such precursors, and source packages of such precursors. The precursors are useful for deposition of Ge 2 Sb 2 Te 5  chalcogenide thin films in the manufacture of nonvolatile Phase Change Memory (PCM), by deposition techniques such as chemical vapor deposition (CVD) and atomic layer deposition (ALD).

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation under 35 U.S.C. §120 of U.S. patentapplication Ser. No. 12/392,009, filed on Feb. 24, 2009, which claimsthe benefit under 35 U.S.C. §119 of U.S. Provisional Patent ApplicationNo. 61/030,980 filed on Feb. 24, 2008 and U.S. Provisional PatentApplication No. 61/050,183 filed on May 2, 2008. The disclosures of U.S.patent application Ser. No. 12/392,009, U.S. Provisional PatentApplication No. 61/030,980 and U.S. Provisional Patent Application No.61/050,183 are hereby incorporated herein by reference in theirrespective entireties, for all purposes.

FIELD OF THE INVENTION

The present invention relates to precursors for use in depositingtellurium-containing films on substrates such as wafers or othermicroelectronic device substrates, as well as associated processes ofmaking and using such precursors, and source packages of suchprecursors.

DESCRIPTION OF THE RELATED ART

In the manufacture of microelectronic devices, there is emerginginterest in the deposition of Ge₂Sb₂Te₅ chalcogenide thin films fornonvolatile Phase Change Memory (PCM), due to its relatively easyintegration pathways with silicon-based integrated circuits. Chemicalvapor deposition (CVD) and atomic layer deposition (ALD) processing ofthese materials are of primary interest as deposition techniques foradvanced device applications.

The anticipated use of high aspect ratio geometries in PCMs and thecorresponding requirement to achieve smooth films of proper phase andnon-segregated character, require processes that are efficient informing high-quality tellurium-containing films at low temperatures(<400° C.). Suitable tellurium precursors are required that arecompatible with such requirements, and that preferably have highvolatility, and are liquids at standard temperature and pressureconditions.

SUMMARY OF THE INVENTION

The present invention relates to tellurium precursors useful fordepositing tellurium-containing films on substrates such as wafers orother microelectronic device substrates, as well as associated processesof making and using such precursors, and source packages of suchprecursors.

In one aspect, the invention relates to a tellurium precursor selectedfrom among:

(i) Te(IV) organyls having the formula TeR¹R²R³R⁴ wherein each of R¹,R², R³ and R⁴ is the same as or different from others, and each isindependently selected from H, halogen, C₁-C₆ alkyl, C₁-C₆ alkoxy, C₃-C₈cycloalkyl, C₆-C₁₀ aryl, silyl, substituted silyl, amide, aminoalkyl,alkylamine, alkoxyalkyl, aryloxyalkyl, imidoalkyl and acetylalkyl;(ii) tellurium bis-amides of the formula Te[NR₂]₂ wherein each R isindependently selected from H, C₁-C₆ alkyl, C₁-C₆ alkoxy, C₃-C₈cycloalkyl, C₆-C₁₀ aryl, silyl, substituted silyl, aminoalkyl,alkoxyalkyl, aryloxyalkyl, imidoalkyl and acetylalkyl;(iii) asymmetric tellurium compounds including one alkyl substituent anda second ligand containing a heteroatom;(iv) tellurium compounds with ethylenediamine ligands;(v) tellurium compounds with dithiocarbamate ligands;(vi) Te(II) and Te(IV) compounds including at least one nitrogen-basedligand selected from among amidinates, guanidinates, isoureates andbeta-diketoiminates; and(vii) dialkyl ditellurides wherein alkyl is C₁-C₈ alkyl.

In another aspect, the invention relates to a compound of the formulaXTeNR¹R²whereinX is halogen; andeach of R¹ and R² is the same as or different from the other, and eachis independently selected from H, C₁-C₆ alkyl, C₁-C₆ alkoxy, C₃-C₈cycloalkyl, C₆-C₁₀ aryl, silyl, substituted silyl, aminoalkyl,alkoxyalkyl, aryloxyalkyl, imidoalkyl and acetylalkyl.

In a further aspect, the invention relates to a composition comprising:

(a) a tellurium precursor selected from among:

(i) Te(IV) organyls having the formula TeR¹R²R³R⁴ wherein each of R¹,R², R³ and R⁴ is the same as or different from others, and each isindependently selected from H, halogen, C₁-C₆ alkyl, C₁-C₆ alkoxy, C₃-C₈cycloalkyl, C₆-C₁₀ aryl, silyl, substituted silyl, amide, aminoalkyl,alkylamine, alkoxyalkyl, aryloxyalkyl, imidoalkyl and acetylalkyl;(ii) tellurium bis-amides of the formula Te[NR₂]₂ wherein each R isindependently selected from H, C₁-C₆ alkyl, C₁-C₆ alkoxy, C₃-C₈cycloalkyl, C₆-C₁₀ aryl, silyl, substituted silyl, aminoalkyl,alkoxyalkyl, aryloxyalkyl, imidoalkyl and acetylalkyl;(iii) asymmetric tellurium compounds including one alkyl substituent anda second ligand containing a heteroatom;(iv) tellurium compounds with ethylenediamine ligands;(v) tellurium compounds with dithiocarbamate ligands;(vi) Te(II) and Te(IV) compounds including at least one nitrogen-basedligand selected from among amidinates, guanidinates, isoureates andbeta-diketoiminates; and(vii) dialkyl ditellurides wherein alkyl is C₁-C₈ alkyl; and(b) a solvent medium in which said compound is dissolved.

A further aspect of the invention relates to a composition comprising

(a) a compound of the formula:ITeNR¹R²whereineach of R¹ and R² is the same as or different from the other, and eachis independently selected from H, C₁-C₆ alkyl, C₁-C₆ alkoxy, C₃-C₈cycloalkyl, C₆-C₁₀ aryl, silyl, substituted silyl, aminoalkyl,alkoxyalkyl, aryloxyalkyl, imidoalkyl and acetylalkyl; and(b) a solvent medium in which said compound is dissolved.

A still further aspect of the invention relates to a precursor vaporcomprising vapor of a tellurium precursor selected from the groupconsisting of

(i) Te(IV) organyls having the formula TeR¹R²R³R⁴ wherein each of R¹,R², R³ and R⁴ is the same as or different from others, and each isindependently selected from H, halogen, C₁-C₆ alkyl, C₁-C₆ alkoxy, C₃-C₈cycloalkyl, C₆-C₁₀ aryl, silyl, substituted silyl, amide, aminoalkyl,alkylamine, alkoxyalkyl, aryloxyalkyl, imidoalkyl and acetylalkyl;(ii) tellurium bis-amides of the formula Te[NR₂]₂ wherein each R isindependently selected from H, C₁-C₆ alkyl, C₁-C₆ alkoxy, C₃-C₈cycloalkyl, C₆-C₁₀ aryl, silyl, substituted silyl, aminoalkyl,alkoxyalkyl, aryloxyalkyl, imidoalkyl and acetylalkyl;(iii) asymmetric tellurium compounds including one alkyl substituent anda second ligand containing a heteroatom;(iv) tellurium compounds with ethylenediamine ligands;(v) tellurium compounds with dithiocarbamate ligands;(vi) Te(II) and Te(IV) compounds including at least one nitrogen-basedligand selected from among amidinates, guanidinates, isoureates andbeta-diketoiminates; and(vii) dialkyl ditellurides wherein alkyl is C₁-C₈ alkyl.

Another aspect of the invention relates to a method of depositing atellurium-containing film on a substrate, comprising volatilizing atellurium precursor to form a precursor vapor, and contacting thesubstrate with the precursor vapor under deposition conditions to formthe tellurium-containing film on the substrate, wherein said telluriumprecursor is selected from the group consisting of:

(i) Te(IV) organyls having the formula TeR¹R²R³R⁴ wherein each of R¹,R², R³ and R⁴ is the same as or different from others, and each isindependently selected from H, halogen, C₁-C₆ alkyl, C₁-C₆ alkoxy, C₃-C₈cycloalkyl, C₆-C₁₀ aryl, silyl, substituted silyl, amide, aminoalkyl,alkylamine, alkoxyalkyl, aryloxyalkyl, imidoalkyl and acetylalkyl;(ii) tellurium bis-amides of the formula Te[NR₂]₂ wherein each R isindependently selected from H, C₁-C₆ alkyl, C₁-C₆ alkoxy, C₃-C₈cycloalkyl, C₆-C₁₀ aryl, silyl, substituted silyl, aminoalkyl,alkoxyalkyl, aryloxyalkyl, imidoalkyl and acetylalkyl;(iii) asymmetric tellurium compounds including one alkyl substituent anda second ligand containing a heteroatom;(iv) tellurium compounds with ethylenediamine ligands;(v) tellurium compounds with dithiocarbamate ligands;(vi) Te(II) and Te(IV) compounds including at least one nitrogen-basedligand selected from among amidinates, guanidinates, isoureates andbeta-diketoiminates; and(vii) dialkyl ditellurides wherein alkyl is C₁-C₈ alkyl.

A further aspect of the invention relates to a packaged precursor,comprising a precursor storage and vapor dispensing vessel havingdisposed therein a tellurium precursor selected from among:

(i) Te(IV) organyls having the formula TeR¹R²R³R⁴ wherein each of R¹,R², R³ and R⁴ is the same as or different from others, and each isindependently selected from H, halogen, C₁-C₆ alkyl, C₁-C₆ alkoxy, C₃-C₈cycloalkyl, C₆-C₁₀ aryl, silyl, substituted silyl, amide, aminoalkyl,alkylamine, alkoxyalkyl, aryloxyalkyl, imidoalkyl and acetylalkyl;(ii) tellurium bis-amides of the formula Te[NR₂]₂ wherein each R isindependently selected from H, C₁-C₆ alkyl, C₁-C₆ alkoxy, C₃-C₈cycloalkyl, C₆-C₁₀ aryl, silyl, substituted silyl, aminoalkyl,alkoxyalkyl, aryloxyalkyl, imidoalkyl and acetylalkyl;(iii) asymmetric tellurium compounds including one alkyl substituent anda second ligand containing a heteroatom;(iv) tellurium compounds with ethylenediamine ligands;(v) tellurium compounds with dithiocarbamate ligands;(vi) Te(II) and Te(IV) compounds including at least one nitrogen-basedligand selected from among amidinates, guanidinates, isoureates andbeta-diketoiminates; and(vii) dialkyl ditellurides wherein alkyl is C₁-C₈ alkyl

Yet another aspect of the invention relates to a method for thepreparation of a tellurium dialkylamide compound, comprising reactingtellurium dihalide with a metal amide to yield said telluriumdialkylamide compound.

A further aspect of the invention relates to a method of forming a GSTfilm on a substrate, comprising depositing tellurium on the substratefrom vapor of a tellurium precursor selected from among:

(i) Te(IV) organyls having the formula TeR¹R²R³R⁴ wherein each of R¹,R², R³ and R⁴ is the same as or different from others, and each isindependently selected from H, halogen, C₁-C₆ alkyl, C₁-C₆ alkoxy, C₃-C₈cycloalkyl, C₆-C₁₀ aryl, silyl, substituted silyl, amide, aminoalkyl,alkylamine, alkoxyalkyl, aryloxyalkyl, imidoalkyl and acetylalkyl;(ii) tellurium bis-amides of the formula Te[NR₂]₂ wherein each R isindependently selected from H, C₁-C₆ alkyl, C₁-C₆ alkoxy, C₃-C₈cycloalkyl, C₆-C₁₀ aryl, silyl, substituted silyl, aminoalkyl,alkoxyalkyl, aryloxyalkyl, imidoalkyl and acetylalkyl;(iii) asymmetric tellurium compounds including one alkyl substituent anda second ligand containing a heteroatom;(iv) tellurium compounds with ethylenediamine ligands;(v) tellurium compounds with dithiocarbamate ligands;(vi) Te(II) and Te(IV) compounds including at least one nitrogen-basedligand selected from among amidinates, guanidinates, isoureates andbeta-diketoiminates; and(vi) Te(II) and Te(IV) compounds including at least one nitrogen-basedligand selected from among amidinates, guanidinates, isoureates andbeta-diketoiminates.

The invention in another aspect relates to a method of making a PCRAMdevice, comprising forming a GST film on a substrate for fabrication ofsaid device, wherein said forming comprises depositing tellurium on thesubstrate from vapor of a tellurium precursor selected from among:

(i) Te(IV) organyls having the formula TeR¹R²R³R⁴ wherein each of R¹,R², R³ and R⁴ is the same as or different from others, and each isindependently selected from H, halogen, C₁-C₆ alkyl, C₁-C₆ alkoxy, C₃-C₈cycloalkyl, C₆-C₁₀ aryl, silyl, substituted silyl, amide, aminoalkyl,alkylamine, alkoxyalkyl, aryloxyalkyl, imidoalkyl and acetylalkyl;(ii) tellurium bis-amides of the formula Te[NR₂]₂ wherein each R isindependently selected from H, C₁-C₆ alkyl, C₁-C₆ alkoxy, C₃-C₈cycloalkyl, C₆-C₁₀ aryl, silyl, substituted silyl, aminoalkyl,alkoxyalkyl, aryloxyalkyl, imidoalkyl and acetylalkyl;(iii) asymmetric tellurium compounds including one alkyl substituent anda second ligand containing a heteroatom;(iv) tellurium compounds with ethylenediamine ligands;(v) tellurium compounds with dithiocarbamate ligands;(vi) Te(II) and Te(IV) compounds including at least one nitrogen-basedligand selected from among amidinates, guanidinates, isoureates andbeta-diketoiminates; and(vi) Te(II) and Te(IV) compounds including at least one nitrogen-basedligand selected from among amidinates, guanidinates, isoureates andbeta-diketoiminates.

The invention in a further aspect relates to a tellurium compoundincluding at least one ethylenediamide ligand, wherein tellurium is inoxidation state (II) or (IV).

Another aspect of the invention relates to a tellurium (IV) compoundselected from the group consisting of:

-   N,N′-di-tert-butylethylenediamide telluriumdichloride;-   2,5-Bis(tert-butyl)-2,5-diaza-1-telluracyclopentane dichloride;-   N-methyl,N′-tert-butylethylenediamide telluriumdichloride;-   N,N′-di-tert-butyl-2,3-dimethylethylenediamide telluriumdichloride;    and-   N,N′-di-tert-butylethylenediamide telluriumchloride dimethylamide.

An additional aspect of the invention relates to a tellurium (IV)compound of the formula:

wherein:R¹, R², R³, R⁴ and R⁵ are the same as or different from one another, andeach is independently selected from C₁-C₆ alkyl, C₁-C₆ alkoxy, C₃-C₈cycloalkyl, C₆-C₁₀ aryl, silyl, substituted silyl, aminoalkyl,alkylamine, alkoxyalkyl, aryloxyalkyl, imidoalkyl, acetylalkyl andhalogen (chlorine, bromine, iodine or fluorine), and each R⁵ canadditionally and independently be hydrogen or amide.

In a further aspect, the invention relates to a tellurium (II) compoundof the formula:

wherein:R¹, R², R³ and R⁴ are the same as or different from one another, andeach is independently selected from C₁-C₆ alkyl, C₁-C₆ alkoxy, C₃-C₈cycloalkyl, C₆-C₁₀ aryl, silyl, substituted silyl, amide, aminoalkyl,alkylamine, alkoxyalkyl, aryloxyalkyl, imidoalkyl, acetylalkyl andhalogen (chlorine, bromine, iodine or fluorine), and R² and R³ canadditionally and independently be hydrogen.

A still further aspect of the invention relates to a method of forming atellurium or tellurium-containing film on a substrate, comprisingvolatilizing a tellurium compound as described above, to form atellurium precursor vapor, and contacting the tellurium precursor vaporwith the substrate to deposit tellurium thereon.

In another aspect, the invention relates to a method of making atellurium (IV) compound, comprising the following reaction:

wherein:R¹, R², R³, R⁴, R⁵, R⁶ and R⁷ are the same as or different from oneanother, and each is independently selected from C₁-C₆ alkyl, C₁-C₆alkoxy, C₃-C₈ cycloalkyl, C₆-C₁₀ aryl, silyl, substituted silyl, amide,aminoalkyl, alkylamine, alkoxyalkyl, aryloxyalkyl, imidoalkyl,acetylalkyl and halogen (chlorine, bromine, iodine or fluorine), and R²and R³ can additionally and independently be hydrogen; andX is halogen (chlorine, bromine, iodine or fluorine).

A further aspect of the invention relates to a method of making atellurium (IV) compound, comprising the following reaction:

wherein:R¹, R², R³, R⁴ and R⁵ are the same as or different from one another, andeach is independently selected from C₁-C₆ alkyl, C₁-C₆ alkoxy, C₃-C₈cycloalkyl, C₆-C₁₀ aryl, silyl, substituted silyl, aminoalkyl,alkylamine, alkoxyalkyl, aryloxyalkyl, imidoalkyl, acetylalkyl andhalogen (chlorine, bromine, iodine or fluorine), and each R⁵ canadditionally and independently be hydrogen or amide;X is a halogen (chlorine, bromine, iodine or fluorine); andM is lithium, sodium or potassium.

In an additional aspect, the invention relates toN,N′-di-tert-butylethylenediamide telluriumdichloride.

A further aspect of the invention relates to NHTe(Cl)NMe₂.

In yet another aspect, the invention relates to a method of making atellurium (II) compound, comprising one of the following reactions(A)-(C):

wherein:R¹, R², R³, R⁴, R⁵, R⁶ and R⁷ are the same as or different from oneanother, and each is independently selected from C₁-C₆ alkyl, C₁-C₆alkoxy, C₃-C₈ cycloalkyl, C₆-C₁₀ aryl, silyl, substituted silyl, amide,aminoalkyl, alkylamine, alkoxyalkyl, aryloxyalkyl, imidoalkyl,acetylalkyl and halogen (chlorine, bromine, iodine or fluorine), and R²and R³ can additionally and independently be hydrogen; andX is halogen (chlorine, bromine, iodine or fluorine);

wherein:M=Li, Na, K;X=chlorine, bromine, iodine or fluorine;R₁, R₂, R₃, R₄ can be the same as or different from one another, andeach is independently selected from C₁-C₆ alkyl, C₁-C₆ alkoxy, C₃-C₈cycloalkyl, C₆-C₁₀ aryl, silyl, substituted silyl, amide, aminoalkyl,alkylamine, alkoxyalkyl, aryloxyalkyl, imidoalkyl, acetylalkyl andhalogen (chlorine, bromine, iodine or fluorine); and

wherein:M=Li, Na, or K;X=Cl, Br, I or F;R₁, R₂, R₃, R₄ can be the same as or different from one another, andeach is independently selected from C₁-C₆ alkyl, C₁-C₆ alkoxy, C₃-C₈cycloalkyl, C₆-C₁₀ aryl, silyl, substituted silyl, amide, aminoalkyl,alkylamine, alkoxyalkyl, aryloxyalkyl, imidoalkyl, acetylalkyl, hydrogenand halogen (chlorine, bromine, iodine or fluorine).

A further aspect of the invention relates to a method of making atellurium (II) compound, comprising the following reaction:

A further aspect of the invention relates to a diorgano ditelluridecompound comprising organo groups each of which is selected from C₁-C₁₂hydrocarbyl groups, silyl and substituted silyl.

The invention also pertains to a method of forming a tellurium ortellurium-containing film on a substrate, comprising vaporizingTe₂(t-Bu)₂ to form a corresponding vapor, and contacting said vapor withsaid substrate to form said tellurium or tellurium-containing filmthereon.

Still another aspect of the invention relates to a packaged telluriumreagent, comprising a reagent storage and dispensing vessel containing atellurium reagent of a type as described above.

In one aspect, the invention further relates to a method of combatingpre-reaction of precursors described herein in a vapor depositionprocess for forming a film on a substrate, wherein the precursorsdescribed herein are susceptible to pre-reaction adversely affecting thefilm. In this aspect, the method involves introducing to the process apre-reaction-combating agent selected from the group consisting of (i)heteroatom (O, N, S) organo Lewis base compounds, (ii) free radicalinhibitors, and (iii) deuterium-containing reagents.

Another aspect of the invention relates to a method of combatingpre-reaction of the precursors described in a vapor deposition processin which multiple feed streams are flowed to a deposition locus to forma film on a substrate, wherein at least one of said multiple feedstreams includes a precursor susceptible to pre-reaction adverselyaffecting the film. The method involves introducing to at least one ofsaid multiple feed streams or supplied materials therefor, or to thedeposition locus, a pre-reaction-combating agent selected from the groupconsisting of (i) heteroatom (O, N, S) organo Lewis base compounds, (ii)free radical inhibitors, and (iii) deuterium-containing reagents.

A still further aspect of the invention relates to a composition,comprising a precursor as described herein and a pre-reaction-combatingagent for said precursor, said pre-reaction-combating agent beingselected from the group consisting of (i) heteroatom (O, N, S) organoLewis base compounds, (ii) free radical inhibitors, and (iii)deuterium-containing reagents.

In a further aspect, the invention relates to a method of combatingpre-reaction of a vapor phase precursor described herein in contact witha substrate for deposition of a film component thereon. The methodinvolves contacting said substrate, prior to said contact of the vaporphase precursor therewith, with a pre-reaction-combating agent selectedfrom the group consisting of (i) heteroatom (O, N, S) organo Lewis basecompounds, (ii) free radical inhibitors, and (iii) deuterium-containingreagents.

In a further aspect, the invention relates to a process wherein thepre-reaction combating reagent is introduced to passivate the surface ofa growing film or slow the deposition rate, followed by reactivationusing an alternative precursor or co-reactant (for example H₂, NH₃,plasma, H₂O, hydrogen sulfide, hydrogen selenide, diorganotellurides,diorganosulfides, diorganoselenides, etc.). Such passivation/retardationfollowed by reactivation thus may be carried out in an alternatingrepetitive sequence, for as many repetitive cycles as desired, in ALD orALD-like processes. Pre-reaction-combating agents can be selected fromthe group consisting of (i) heteroatom (O, N, S) organo Lewis basecompounds, (ii) free radical inhibitors, and (iii) deuterium-containingreagents.

Another aspect of the invention relates to a vapor phase depositionprocess for forming a film on a substrate involving cyclic contacting ofthe substrate with at least one film precursor described herein that isundesirably pre-reactive in the vapor phase. The process involvesintroducing to said film during growth thereof a pre-reaction-combatingreagent that is effective to passivate a surface of said film or to slowrate of deposition of said film precursor, and after introducing saidpre-reaction-combating reagent, reactivating said film with a differentfilm precursor.

Other aspects, features and embodiments of the invention will be morefully apparent from the ensuing disclosure and appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic representation of a material storage anddispensing package containing a precursor of the present invention, inone embodiment thereof.

FIG. 2 is an ORTEP diagram of the structure of NHTeCl₂, i.e.,N,N′-di-tert-butylethylenediamide telluriumdichloride.

FIG. 3 is an ORTEP diagram of the structure of Me₂NHTeCl₂.

FIG. 4 is an ORTEP diagram of the structure of NHTe(Cl)NMe₂.

FIG. 5 is an ORTEP diagram of the structure of Te₂(t-Bu)₂.

FIG. 6 is a simultaneous thermographic analysis plot of STA TG/DSC datafor Te₂(t-Bu)_(2.)

FIG. 7 is a STA of Te[N(SiMe₃)₂]₂.

FIG. 8 is a STA of Te[N(SiMe₃)(t-Bu)]₂.

FIG. 9 is a schematic representation of a vapor deposition systemaccording to one embodiment of the present invention, whereinsuppression of pre-reaction of the precursors is achieved by addition ofpre-reaction-combating reagent to one or more feed streams in the vapordeposition system.

DETAILED DESCRIPTION OF THE INVENTION, AND PREFERRED EMBODIMENTS THEREOF

The present invention relates to tellurium precursors useful infilm-forming applications, e.g., in chemical vapor deposition and atomiclayer deposition applications, to form correspondingtellurium-containing films on substrates, as well as associatedprocesses of making and using such precursors, and packaged forms ofsuch precursors.

As used herein, the term “film” refers to a layer of deposited materialhaving a thickness below 1000 micrometers, e.g., from such value down toatomic monolayer thickness values. In various embodiments, filmthicknesses of deposited material layers in the practice of theinvention may for example be below 100, 10, or 1 micrometers, or invarious thin film regimes below 200, 100, or 50 nanometers, depending onthe specific application involved. As used herein, the term “thin film”means a layer of a material having a thickness below 1 micrometer.

As used herein, the singular forms “a”, “and”, and “the” include pluralreferents unless the context clearly dictates otherwise.

As used herein, the identification of a carbon number range, e.g., inC₁-C₁₂ alkyl, is intended to include each of the component carbon numbermoieties within such range, so that each intervening carbon number andany other stated or intervening carbon number value in that statedrange, is encompassed, it being further understood that sub-ranges ofcarbon number within specified carbon number ranges may independently beincluded in smaller carbon number ranges, within the scope of theinvention, and that ranges of carbon numbers specifically excluding acarbon number or numbers are included in the invention, and sub-rangesexcluding either or both of carbon number limits of specified ranges arealso included in the invention. Accordingly, C₁-C₁₂ alkyl is intended toinclude methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl,nonyl, decyl, undecyl and dodecyl, including straight chain as well asbranched groups of such types. It therefore is to be appreciated thatidentification of a carbon number range, e.g., C₁-C₁₂, as broadlyapplicable to a substituent moiety, enables, in specific embodiments ofthe invention, the carbon number range to be further restricted, as asub-group of moieties having a carbon number range within the broaderspecification of the substituent moiety. By way of example, the carbonnumber range C₁-C₁₂ alkyl, may be more restrictively specified, inparticular embodiments of the invention, to encompass sub-ranges such asC₁-C₄ alkyl, C₂-C₈ alkyl, C₂-C₄ alkyl, C₃-C₅ alkyl, or any othersub-range within the broad carbon number range.

The precursors of the invention may be further specified in specificembodiments by provisos or limitations excluding specific substituents,groups, moieties or structures, in relation to various specificationsand exemplifications thereof set forth herein. Thus, the inventioncontemplates restrictively defined compositions, e.g., a compositionwherein R^(i) is C₁-C₁₂ alkyl, with the proviso that R^(i)≠C₄ alkyl whenR^(j) is silyl.

The invention relates in one aspect to Te(IV) organyls useful for lowtemperature (T<400° C.) deposition of Te-containing films, e.g., forforming germanium-antimony-tellurium (GST) films such as Ge₂Sb₂Te₅ onsubstrates such as wafers in the production of phase change randomaccess memory devices.

The Te(IV) organyls of the invention are suitable for forming such filmsby techniques such as atomic layer deposition (ALD) and chemical vapordeposition (CVD). Preferred precursors of such type are liquid at roomtemperature (25° C.) and have high volatility and desirable transportproperties for ALD and CVD applications.

In accordance with another aspect of the invention, Te(IV) organylshaving the formula TeR¹R²R³R⁴ wherein R¹, R², R³ and R⁴ are organosubstituents, are employed to form Te-containing highly conformal filmsof superior character by a vapor deposition process such as ALD or CVD.

In a preferred aspect, Te(IV) organyls are utilized having the formulaTeR¹R²R³R⁴ wherein each of R¹, R², R³ and R⁴ is the same as or differentfrom others, and each is independently selected from H, halogen(fluorine, bromine, iodine and chlorine), C₁-C₆ alkyl, C₁-C₆ alkoxy,C₃-C₈ cycloalkyl, C₆-C₁₀ aryl, silyl, substituted silyl (silyl havingC₁-C₆ alkyl substituents and/or C₆-C₁₀ aryl substituents), amide,aminoalkyl, alkylamine, alkoxyalkyl, aryloxyalkyl, imidoalkyl andacetylalkyl. The alkyl moiety in such aminoalkyl, alkylamine,alkoxyalkyl, aryloxyalkyl, imidoalkyl and acetylalkyl substituents canbe C₁-C₆ alkyl or alkyl moieties of other carbon numbers, as may beuseful in a given application of such organyl compounds.

Tellurium(IV) organyls of the invention useful for the aforementionedfilm-forming applications can readily be formed by the followinggeneralized reaction:TeCl₄+4RM→TeR₄+MClwherein M is Li or MgX, X is halide, and each R independently may be H,halogen (fluorine, bromine, iodine and chlorine), C₁-C₆ alkyl, C₁-C₆alkoxy, C₃-C₈ cycloalkyl, C₆-C₁₀ aryl, silyl, substituted silyl, amide,aminoalkyl, alkylamine, alkoxyalkyl, aryloxyalkyl, imidoalkyl oracetylalkyl, as above described.

The Te(IV) compounds of the invention are usefully employed as CVD/ALDprecursors for the deposition of Te-containing films, e.g., by liquiddelivery techniques in which such compounds are provided in compositionsincluding suitable solvent media. Useful solvents for such purpose inspecific applications may include, without limitation, alkanes (e.g.,hexane, heptane, octane, and pentane), aromatics (e.g., benzene ortoluene), and amines (e.g., triethylamine, tert-butylamine). The solventmedium in which the Te precursor or precursors are dissolved orsuspended may be a single-component solvent or a multi-component solventcomposition.

The precursors when in a liquid state can also be delivered neat usingALD/CVD liquid delivery techniques, in which the liquid is volatilizedto form a corresponding precursor vapor, which then is contacted withthe substrate on which the tellurium-containing film is to be formed,under appropriate vapor deposition conditions.

When the precursors are in a solid state, they may be volatilized fordelivery using any suitable solid delivery system, such as the soliddelivery and vaporizer unit commercially available under the trademarkProE-Vap from ATMI, Inc. (Danbury, Conn., USA). The precursor orprecursors (since the invention contemplates use of multiple Teprecursors of differing type) are volatilized to form the correspondingprecursor vapor which then is contacted with a wafer or other substrateto deposit a tellurium-containing layer thereon.

The precursor vapor formed from the Te precursor may be mixed withcarrier or co-reactant gases in various embodiments, to obtain desireddeposition thicknesses, growth rates, etc., as will be apparent to thoseskilled in the art.

The present invention in various aspects involves compositions andmethods in which tellurium dialkyls and ditellurium dialkyls can beutilized as tellurium source reagents, but in other aspects, non-alkyltellurium and non-alkyl ditellurium compounds are utilized.

The invention in a further aspect relates to a synthetic route for thepreparation of tellurium amide compounds, e.g., tellurium bis-amidesthat are useful for low temperature deposition of tellurium amides onsubstrates.

The tellurium amide compounds can be formed by reacting telluriumdihalide with two equivalents of a metal amide, according to thefollowing reaction.TeX₂+2MNR₂→Te[NR₂]₂+2MXwherein:X is halogen, preferably Cl, Br or I,M is Li, Na, or K, andeach R is independently selected from among H, C₁-C₆ alkyl, C₁-C₆alkoxy, C₃-C₈ cycloalkyl, C₆-C₁₀ aryl, silyl, substituted silyl,aminoalkyl, alkoxyalkyl, aryloxyalkyl, imidoalkyl and acetylalkyl, asabove described.

In one preferred embodiment, TeI_(e) is reacted with LiN(t-Bu)(SiMe₃) toform the reaction product Te[N(t-Bu)(SiMe₃)]₂.

wherein t-butyl is tertiary butyl, and Me is methyl.

This product, Te[N(t-Bu)(SiMe₃)]_(z), has been characterized by NMRspectroscopy and thermal analysis (STA), as a low melting solid (mp=77°C.) that shows good transport properties (T50=184° C.) and low residualmass (<2%). This compound is usefully employed as a precursor for thelow temperature deposition of tellurium-containing films.

In another preferred embodiment, TeI₂ is reacted with KN(SiMe₃)₂ to formthe following reaction product, Te[N(SiMe₃)₂]₂.

A further aspect of the invention relates to asymmetric telluriumcompounds including one alkyl substituent and a second ligand containinga heteroatom, e.g., nitrogen or sulfur. The second ligand may be of anysuitable type, and in specific embodiments is amidinate, guanidinate, ordithiocarbamate.

In one embodiment, the starting material for the asymmetric telluriumcompound is ITeN R¹R² wherein each of R¹ and R² is the same as ordifferent from the other, and each is independently selected from H,C₁-C₆ alkyl, C₁-C₆ alkoxy, C₃-C₈ cycloalkyl, C₆-C₁₀ aryl, silyl,substituted silyl, aminoalkyl, alkoxyalkyl, aryloxyalkyl, imidoalkyl andacetylalkyl, as above described. This starting material can besynthesized by the reaction of TeI₂ with one equivalent of a lithiumamide as shown below.

or, more generally, halide starting materials can be formed according tothe following reaction.TeX₂+MNR₁R₂→XTeNR₁R₂+MXwhereinM is Li, Na, or K, preferably Li,X is halogen, preferably Cl, Br or I, andeach of R₁ and R₂ is the same as or different from the other, and eachis independently selected from H, C₁-C₆ alkyl, C₁-C₆ alkoxy, C₃-C₈cycloalkyl, C₆-C₁₀ aryl, silyl, substituted silyl, aminoalkyl,alkoxyalkyl, aryloxyalkyl, imidoalkyl and acetylalkyl, as abovedescribed.

The starting material ITeN R¹R² is extremely sensitive to light and airwhen isolated as an orange solid product, however, it can be placed intosolution with a suitable solvent medium, e.g., a hydrocarbon solventmedium, containing pentane, hexane or toluene, or other hydrocarbonspecies. Such starting material ITeN R¹R² can be reacted in situ in thehydrocarbon solvent medium with an alkyl lithium reagent to obtain anasymmetric tellurium compound, as shown in the reaction below.XTeNR¹R²+MR³→R³TeNR¹R²+MXwhereinM is Li, Na, or K, preferably Li,X is halogen, preferably Cl, Br or I, andeach of R¹, R² and R³ is the same as or different from the other, andeach is independently selected from H, C₁-C₆ alkyl, C₁-C₆ alkoxy, C₃-C₈cycloalkyl, C₆-C₁₀ aryl, silyl, substituted silyl, aminoalkyl,alkoxyalkyl, aryloxyalkyl, imidoalkyl and acetylalkyl, as abovedescribed, and wherein R³ can in addition be amide or halogen.

Using the same synthetic approach, other ligands, such as:

amidinates

wherein each of R₁, R₂, R₃ and R₄ is the same as or different fromothers, and each is independently selected from H, C₁-C₆ alkyl, C₁-C₆alkoxy, C₃-C₈ cycloalkyl, C₆-C₁₀ aryl, silyl, substituted silyl,aminoalkyl, alkoxyalkyl, aryloxyalkyl, imidoalkyl and acetylalkyl, andwherein R₄ can in addition be halogen or amide;guanidinates

wherein each of R₁, R₂, R₃, R₄ and R₅ is the same as or different fromothers, and each is independently selected from H, C₁-C₆ alkyl, C₁-C₆alkoxy, C₃-C₈ cycloalkyl, C₆-C₁₀ aryl, silyl, substituted silyl,aminoalkyl, alkoxyalkyl, aryloxyalkyl, imidoalkyl and acetylalkyl, andwherein R₅ can in addition be halogen or amide; anddithiocarbamates

wherein each of R₁, R₂ and R₃ is the same as or different from others,and each is independently selected from H, C₁-C₆ alkyl, C₁-C₆ alkoxy,C₃-C₈ cycloalkyl, C₆-C₁₀ aryl, silyl, substituted silyl, alkoxyalkyl,aryloxyalkyl, imidoalkyl and acetylalkyl and wherein R³ can in additionbe halogen or amide,can be synthesized as well.

The invention therefore provides asymmetric tellurium compoundsincluding tellurium amides, amidinates, guanidinates anddithiocarbamates of a useful character for ALD or CVD deposition oftellurium or tellurium-containing films, e.g., for fabricating GSTdevices comprising Ge₂Sb₂Te₅ films.

Another aspect of the invention relates to tellurium compounds withethylenediamine ligands and tellurium compounds with dithiocarbamateligands, for use in low temperature deposition applications such asfabrication of the aforementioned GST-based phase change memory devices.

Tellurium complexes with ethylenediamine type ligands can besynthesized, according to one preferred aspect of the invention, byreacting a lithium salt of the ethylenediamine with a tellurium halide,such as TeX₂ or TeX₄, wherein X is halogen. From the resulting reactionproduct, the desired tellurium compounds can be obtained by a saltelimination reaction.

The following reaction scheme therefore may be used for production ofsuch tellurium precursors.

whereinM=Li, Na, or K;X=Cl, Br, or I;each of R¹, R², R³ and R⁴ is the same as or different from others, andeach is independently selected from H, C₁-C₆ alkyl, C₁-C₆ alkoxy, C₃-C₈cycloalkyl, C₆-C₁₀ aryl, silyl, substituted silyl, aminoalkyl,alkoxyalkyl, aryloxyalkyl, imidoalkyl and acetylalkyl.

Alternatively, the following reaction scheme can be employed to producethe tellurium ethylenediamine precursors.

whereinM=Li, Na, or K;X=Cl, Br, or I;each of R¹, R², R³ and R⁴ is the same as or different from others, andeach is independently selected from H, C₁-C₆ alkyl, C₁-C₆ alkoxy, C₃-C₈cycloalkyl, C₆-C₁₀ aryl, silyl, substituted silyl, aminoalkyl,alkoxyalkyl, aryloxyalkyl, imidoalkyl and acetylalkyl.

A specific synthesis procedure for forming a tellurium precursor withethylenediamine ligands is set forth below.

Tellurium ethylenediamine compounds of such type have high volatilityand low decomposition temperatures, and thus are well suited for ALD andCVD applications.

Complexes of tellurium with only dithiocarbamate ligands, or includingdithiocarbamate and other co-ligands, constitute a further group ofprecursors useful for ALD and CVD in accordance with the invention.Tellurium dithiocarbamate precursors of the invention include thefollowing classes (a)-(e):

whereinM is Li, Na, or K, preferably Li,X is halogen, preferably Cl, Br or I, andeach R is the same as or different from the other, and each isindependently selected from H, C₁-C₆ alkyl, C₁-C₆ alkoxy, C₃-C₈cycloalkyl, C₆-C₁₀ aryl, silyl, substituted silyl, aminoalkyl,alkoxyalkyl, aryloxyalkyl, imidoalkyl and acetylalkyl;

whereineach of R₁, R₂, R₃ and R₄ is the same as or different from others, andeach is independently selected from H, C₁-C₆ alkyl, C₁-C₆ alkoxy, C₃-C₈cycloalkyl, C₆-C₁₀ aryl, silyl, substituted silyl, aminoalkyl,alkoxyalkyl, aryloxyalkyl, imidoalkyl and acetylalkyl, and wherein R₃and R₄ can in addition and independently be halogen or amide;

whereineach of R₁ and R₂ is the same as or different from the other, and eachis independently selected from H, C₁-C₆ alkyl, C₁-C₆ alkoxy, C₃-C₈cycloalkyl, C₆-C₁₀ aryl, silyl, substituted silyl, aminoalkyl,alkoxyalkyl, aryloxyalkyl, imidoalkyl and acetylalkyl;

wherein:each of R₁, R₂, R₃, R₄ and R₅ is the same as or different from others,and each is independently selected from H, C₁-C₆ alkyl, C₁-C₆ alkoxy,C₃-C₈ cycloalkyl, C₆-C₁₀ aryl, silyl, substituted silyl, aminoalkyl,alkoxyalkyl, aryloxyalkyl, imidoalkyl and acetylalkyl, and wherein eachof R₃, R₄ and R₅ can in addition and independently be amide or halogen;and

wherein each of R₁, R₂ and R₃ is the same as or different from others,and each is independently selected from H, C₁-C₆ alkyl, C₁-C₆ alkoxy,C₃-C₈ cycloalkyl, C₆-C₁₀ aryl, silyl, substituted silyl, aminoalkyl,alkoxyalkyl, aryloxyalkyl, imidoalkyl and acetylalkyl, and wherein R₃can in addition be halogen or amide.

These precursors accommodate low temperature deposition applications,having good volatilization and transport properties. They can bedelivered in a neat form in the case of precursor compounds in liquidform, or in compositions including suitable solvent media. Usefulsolvents for such purpose in specific applications may include, withoutlimitation, alkanes (e.g., hexane, heptane, octane, and pentane),aromatics (e.g., benzene or toluene), and amines (e.g., triethylamine,tert-butylamine) or mixtures thereof, as above described.

The precursors when in a solid state can be volatilized for deliveryusing any suitable solid delivery system, such as the solid delivery andvaporizer unit commercially available under the trademark ProE-Vap fromATMI, Inc. (Danbury, Conn., USA). The precursor or precursors (since theinvention contemplates use of multiple Te precursors of differing type)are volatilized to form the corresponding precursor vapor which then iscontacted with a wafer or other substrate to deposit atellurium-containing layer thereon, e.g., for forming a GST layer.

The invention in yet another aspect relates to tellurium compounds withnitrogen donor ligands useful for deposition applications to deposittellurium or tellurium-containing films on substrates, for applicationssuch as GST phase change random access memory (PRAM) devices.

This aspect of the invention relates more specifically to Te(II) andTe(IV) precursors having at least one nitrogen-based ligand selectedfrom among amidinates, guanidinates, isoureates and beta-diketoiminates.

Specific tellurium nitrogen donor ligand precursors of the inventioninclude the following:

(A) Te(II) amidinates, guanidinates, and isoureates of the formula

wherein:each of R₁, R₂ and R₃ is the same as or different from others, and eachis independently selected from H, C₁-C₆ alkyl, C₁-C₆ alkoxy, C₃-C₈cycloalkyl, C₆-C₁₀ aryl, silyl, substituted silyl, aminoalkyl,alkoxyalkyl, aryloxyalkyl, imidoalkyl and acetylalkyl, and wherein R³can in addition be halogen or amide; andZ is independently selected from C₁-C₆ alkoxy, —NR₁R₂, H, C₁-C₆ alkyl,C₃-C₁₀ cycloalkyl, and C₆-C₁₃ aryl;(B) Te(IV) amidinates, guanidinates, and isoureates of the formula

wherein:each of R₁, R₂ and R₃ is the same as or different from others, and eachis independently selected from H, C₁-C₆ alkyl, C₁-C₆ alkoxy, C₃-C₈cycloalkyl, C₆-C₁₀ aryl, silyl, substituted silyl, aminoalkyl,alkoxyalkyl, aryloxyalkyl, imidoalkyl and acetylalkyl, and wherein eachR₃ can in addition and independently be halogen or amide;Z is independently selected from C₁-C₆ alkoxy, —NR₁R₂, H, C₁-C₆ alkyl,C₃-C₁₀ cycloalkyl, and C₆-C₁₃ aryl; andx is an integer having a value of from 0 to 4, inclusive;(C) Te(II) beta-diketoiminates of the formula

whereineach of R₁, R₂, R₃ and R₄ is the same as or different from others, andeach is independently selected from H, halogen, C₁-C₆ alkyl, C₁-C₆alkoxy, C₃-C₈ cycloalkyl, C₆-C₁₀ aryl, silyl, substituted silyl, amide,aminoalkyl, alkylamine, alkoxyalkyl, aryloxyalkyl, imidoalkyl andacetylalkyl; and(D) Te(IV) beta-diketoiminates of the formula

whereineach of R₁, R₂, R₃, R₄, R₅ and R₆ is the same as or different fromothers, and each is independently selected from H, halogen, C₁-C₆ alkyl,C₁-C₆ alkoxy, C₃-C₈ cycloalkyl, C₆-C₁₀ aryl, silyl, substituted silyl,amide, aminoalkyl, alkylamine, alkoxyalkyl, aryloxyalkyl, imidoalkyl andacetylalkyl.

The tellurium compounds of the invention in film formation processes maybe used with appropriate co-reactants, e.g., in a continuous depositionmode (CVD) or pulsed/atomic layer deposition mode (ALD), to depositfilms of superior character. For oxides, preferred co-reactants includeO₂ and N₂O for CVD, and more aggressive oxidizers for pulsed deposition,e.g., H₂O, ozone, and O₂ plasma. For metal-like films, reducingatmospheres are advantageously used.

The precursors of the invention can be utilized as low temperaturedeposition precursors with reducing co-reactants such as hydrogen,H₂/plasma, amines, imines, hydrazines, silanes, germanes such as GeH₄,ammonia, alkanes, alkenes and alkynes. For CVD modes of film formation,reducing agents such as H₂, and NH₃ are preferred, and plasmas of theseco-reactants may be used in digital or ALD mode, wherein theco-reactants are separated from the precursor in a pulse train,utilizing general CVD and ALD techniques within the skill of the art,based on the disclosure herein. More aggressive reducing agents can alsobe used in a digital or ALD mode since co-reactants can be separated,preventing gas phase reactions. For ALD and conformal coverage in highaspect ratio structures, the precursor preferably exhibits self-limitingbehavior in one type of atmosphere (e.g., inert or weaklyreducing/oxidizing gas environments) and exhibits rapid decomposition toform a desired film in another type of atmosphere (e.g., plasma,strongly reducing/oxidizing environments).

Liquid delivery formulations can be employed in which precursors thatare liquids may be used in neat liquid form, or liquid or solidprecursors may be employed in suitable solvents, including for examplealkane solvents (e.g., hexane, heptane, octane, and pentane), arylsolvents (e.g., benzene or toluene), amines (e.g., triethylamine,tert-butylamine), imines and hydrazines or mixtures thereof. The utilityof specific solvent compositions for particular Te precursors may bereadily empirically determined, to select an appropriate singlecomponent or multiple component solvent medium for the liquid deliveryvaporization and transport of the specific tellurium precursor that isemployed. In the case of solid precursors of the invention, a soliddelivery system may be utilized, for example, using the ProE-Vap soliddelivery and vaporizer unit (commercially available from ATMI, Inc.,Danbury, Conn., USA).

In general, the thicknesses of metal-containing layers formed using theprecursors of the invention can be of any suitable value. In a specificembodiment of the invention, the thickness of the tellurium-containinglayer can be in a range of from 5 nm to 500 nm or more.

The various tellurium precursor compounds of the invention can beutilized to form GST films in combination any with suitable germaniumand antimony precursors, e.g., by CVD and ALD techniques, forapplications such as PCRAM device manufacture. The process conditionsuseful for carrying out deposition of Te-containing films can be readilydetermined within the skill of the art by the simple expedient ofselectively varying the delivery and deposition process conditions andcharacterizing the resulting films, to determine the process conditionsenvelope most appropriate for a given deposition application.

In one specific embodiment of the invention, Te[N(SiMe₃)₂]₂ is used as atellurium precursor for forming tellurium-containing films onsubstrates, such as GST films, amorphous GeTe films, and SbTe films, byatomic layer deposition (ALD) and chemical vapor deposition (CVD)techniques.

In another embodiment, amorphous GeTe and SbTe are deposited fromdi-t-butyl tellurium, Te(tBu)₂, at temperature in a range of from 300°C.-350° C., e.g., 320° C., using bubbler delivery of the telluriuimprecursor in an inert carrier gas stream, e.g., N₂ at a flow rate of20-50 sccm, e.g., 30 sccm. The respective germanium and antimonyprecursors used for such deposition can be of any suitable types, e.g.,GeBAMDN, SbTDMA, etc., and such precursors can be delivered fordeposition at any suitable volumetric flow rate, e.g., for theaforementioned flow rate of 30 sccm for the illustrative telluriumprecursor, Te(tBu)₂, a flow rate of such Ge or Sb precursor can be onthe order of 5 micromoles/minute. The resulting amorphous GeTe and SbTefilms will have a tellurium content of approximately 40%.

FIG. 1 is a schematic representation of a material storage anddispensing package 100 containing a tellurium precursor, according toone embodiment of the present invention.

The material storage and dispensing package 100 includes a vessel 102that may for example be of generally cylindrical shape as illustrated,defining an interior volume 104 therein. In this specific embodiment,the precursor is a solid at ambient temperature conditions, and suchprecursor may be supported on surfaces of the trays 106 disposed in theinterior volume 104 of the vessel, with the trays having flow passageconduits 108 associated therewith, for flow of vapor upwardly in thevessel to the valve head assembly for dispensing, in use of the vessel.

The solid precursor can be coated on interior surfaces in the interiorvolume of the vessel, e.g., on the surfaces of the trays 106 andconduits 108. Such coating may be effected by introduction of theprecursor into the vessel in a vapor form from which the solid precursoris condensed in a film on the surfaces in the vessel. Alternatively, theprecursor solid may be dissolved or suspended in a solvent medium anddeposited on surfaces in the interior volume of the vessel by solventevaporation. In yet another method the precursor may be melted andpoured onto the surfaces in the interior volume of the vessel. For suchpurpose, the vessel may contain substrate articles or elements thatprovide additional surface area in the vessel for support of theprecursor film thereon.

As a still further alternative, the solid precursor may be provided ingranular or finely divided form, which is poured into the vessel to beretained on the top supporting surfaces of the respective trays 106therein. As a further alternative, a metal foam body may be provided inthe interior volume of the vessel, which contains porosity of a specificcharacter adapted for retaining the solid particulate precursor forhighly efficient vaporization thereof.

The vessel 102 has a neck portion 109 to which is joined the valve headassembly 110. The valve head assembly is equipped with a hand wheel 112in the embodiment shown. In lieu of a hand wheel, the valve headassembly may in turn be coupled or operatively linked to a controllerfor automated operation. The valve head assembly 110 includes adispensing port 114, which may be configured for coupling to a fittingor connection element to join flow circuitry to the vessel. Such flowcircuitry is schematically represented by arrow A in FIG. 1, and theflow circuitry may be coupled to a downstream ALD or chemical vapordeposition chamber (not shown in FIG. 1).

In use, the vessel 102 can be heated with a suitable heater, such as aheating jacket, resistance heating elements affixed to the exterior wallsurface of the vessel, etc., so that solid precursor in the vessel is atleast partially volatilized to provide precursor vapor. The input ofheat is schematically shown in FIG. 1 by the reference arrow Q. Theprecursor vapor is discharged from the vessel through the valve passagesin the valve head assembly 110 when the hand wheel 112 or alternativevalve actuator or controller is translated so that the valve is in anopen position, whereupon vapor deriving from the precursor is dispensedinto the flow circuitry schematically indicated by arrow A.

In lieu of solid delivery of the precursor, the precursor may beprovided in a solvent medium, forming a solution or suspension. Suchprecursor-containing solvent composition then may be delivered by liquiddelivery and flash vaporized to produce a precursor vapor. The precursorvapor is contacted with a substrate under deposition conditions, todeposit the metal on the substrate as a film thereon.

In one embodiment, the precursor is dissolved in an ionic liquid medium,from which precursor vapor is withdrawn from the ionic liquid solutionunder dispensing conditions.

As a still further alternative, the precursor may be stored in anadsorbed state on a suitable solid-phase physical adsorbent storagemedium in the interior volume of the vessel. In use, the precursor vaporis dispensed from the vessel under dispensing conditions involvingdesorption of the adsorbed precursor from the solid-phase physicaladsorbent storage medium.

Supply vessels for precursor delivery may be of widely varying type, andmay employ vessels such as those commercially available from ATMI, Inc.(Danbury, Conn.) under the trademarks SDS, SAGE, VAC, VACSorb, andProE-Vap, as may be appropriate in a given storage and dispensingapplication for a particular precursor of the invention.

The precursors of the invention thus may be employed to form precursorvapor for contacting with a substrate to deposit a tellurium-containingthin film thereon.

In a preferred aspect, the invention utilizes the precursors to conductatomic layer deposition, yielding ALD films of superior conformalitythat are uniformly coated on the substrate with high step coverage andconformality even on high aspect ratio structures.

Accordingly, the precursors of the present invention enable a widevariety of microelectronic devices, e.g., semiconductor products, flatpanel displays, etc., to be fabricated with tellurium-containing filmsof superior quality.

The invention in another aspect relates to a class of telluriumcompounds with ethylenediamide-type ligands. Such tellurium compoundsare useful as precursors for low temperature ALD/CVD of tellurium ortellurium-containing thin films, e.g., for applications such asfabrication of phase change memory devices based on Ge₂Sb₂Te₅ (GST).This class of compounds includes tellurium (Te) in the oxidation stateIV, which is characterized by greater stability than commonly usedtellurium precursors in the oxidation state II, thereby affording abeneficial alternative to the commonly used Te(II) precursors which arenotoriously unstable with respect to air- and light-sensitivity.

These tellurium compounds are to our knowledge the first examples oftellurium amides in which tellurium is in oxidation state (IV). Examplesof such tellurium (IV) amides include, without limitation:

Formula Compound NHTeCl₂ N,N′-di-tert-butylethylenediamidetelluriumdichloride NHTeCl₂2,5-Bis(tert-butyl)-2,5-diaza-1-telluracyclopentane dichloride MeNHTeCl₂N-methyl,N′-tert-butylethylenediamide telluriumdichloride DMNHTeCl₂N,N′-di-tert-butyl-2,3-dimethylethylenediamide telluriumdichlorideNHTe(Cl)NMe₂ N,N′-di-tert-butylethylenediamide telluriumchloridedimethylamidewherein the term NH is an abbreviation for “N-heterocyclic,” and denotesan N-heterocyclic ring system containing tellurium.

The general synthetic concept for such tellurium (IV) compounds,described more fully below, is also potentially applicable to thesynthesis of tellurium (II) compounds. The general synthetic scheme(Scheme I below) is based on reaction of a tellurium (IV) halide with anethylenediamide type ligand, with the addition of a tertiary amine inorder to scavenge the eliminated hydrochloride.

wherein:R¹, R², R³, R⁴, R⁵, R⁶ and R⁷ are the same as or different from oneanother, and each is independently selected from C₁-C₆ alkyl, C₁-C₆alkoxy, C₃-C₈ cycloalkyl, C₆-C₁₀ aryl, silyl, substituted silyl, amide,aminoalkyl, alkylamine, alkoxyalkyl, aryloxyalkyl, imidoalkyl,acetylalkyl and halogen (chlorine, bromine, iodine or fluorine), and R²and R³ can additionally and independently be hydrogen; andX is halogen (chlorine, bromine, iodine or fluorine).

Derivatives of the ethylenediamide tellurium complexes can besynthesized according to the following reaction scheme (Scheme II), byreacting the corresponding dichloride with a lithium alkyl or lithiumamide species.

wherein:R¹, R², R³, R⁴ and R⁵ are the same as or different from one another, andeach is independently selected from C₁-C₆ alkyl, C₁-C₆ alkoxy, C₃-C₈cycloalkyl, C₆-C₁₀ aryl, silyl, substituted silyl, aminoalkyl,alkylamine, alkoxyalkyl, aryloxyalkyl, imidoalkyl, acetylalkyl andhalogen (chlorine, bromine, iodine or fluorine), and each R⁵ canadditionally and independently be hydrogen or amide;X is a halogen selected from chloride, bromide and iodide; andM is lithium, sodium or potassium.

The foregoing synthesis reactions can be carried out in any suitablesolvent medium. One preferred solvent medium comprises an ether typesolvent or other somewhat polar solvent in which the tellurium halide issufficiently soluble. Tetrahydrofuran (THF) is one preferred solventspecies, while diethyl ether, dimethoxyethane and toluene are alsohighly advantageous species. The choice of a specific solvent medium maybe readily empirically determined, based on considerations ofsolubility, yields and reaction times for specific desired telluriumprecursor products.

As one example of the tellurium (IV) amide compounds of the invention,FIG. 2 is an ORTEP diagram of the structure of NHTeCl₂, i.e.,N,N′-di-tert-butylethylenediamide telluriumdichloride. This compound isreadily purified to high purity by sublimation, and has been confirmedby X-ray crystal structure analysis as existing in a weakly associateddimer solid state. As another example of such tellurium (IV) amidecompounds, FIG. 3 is an ORTEP diagram of the structure of Me₂NHTeCl₂,also confirmed by X-ray crystal structure analysis to exist in a weaklyassociated dimer solid state.

FIG. 4 is an ORTEP diagram of the structure of NHTe(Cl)NMe₂. Thistellurium source compound can be synthesized by a reaction scheme asdescribed above. Such reaction scheme can be utilized to produce amono-substituted species under mild reaction conditions, e.g., stirringof the reaction volume at room temperature, while a large excess ofamide and harsher conditions, such as several days under refluxconditions, can be utilized to produce the disubstituted compound.

Corresponding compounds of tellurium (II) can be synthesized by thefollowing related reaction scheme (Scheme III) conducted in acorresponding solvent medium:

wherein:R¹, R², R³, R⁴, R⁵, R⁶ and R⁷ are the same as or different from oneanother, and each is independently selected from C₁-C₆ alkyl, C₁-C₆alkoxy, C₃-C₈ cycloalkyl, C₆-C₁₀ aryl, silyl, substituted silyl, amide,aminoalkyl, alkylamine, alkoxyalkyl, aryloxyalkyl, imidoalkyl,acetylalkyl and halogen (chlorine, bromine, iodine or fluorine), and R²and R³ can additionally and independently be hydrogen; andX is halogen (chlorine, bromine, iodine or fluorine).

Another synthesis for such tellurium (II) compounds is set out below inScheme IIIA:

wherein:M=Li, Na, K;X=chlorine, bromine, iodine or fluorine;R₁, R₂, R₃, R₄ can be the same as or different from one another, andeach is independently selected from C₁-C₆ alkyl, C₁-C₆ alkoxy, C₃-C₈cycloalkyl, C₆-C₁₀ aryl, silyl, substituted silyl, amide, aminoalkyl,alkylamine, alkoxyalkyl, aryloxyalkyl, imidoalkyl, acetylalkyl andhalogen (chlorine, bromine, iodine or fluorine).

A still further synthesis of such tellurium (II) compounds is set out inScheme IIIB below:

wherein:M=Li, Na, or K;X=Cl, Br, I or F;R₁, R₂, R₃, R₄ can be the same as or different from one another, andeach is independently selected from C₁-C₆ alkyl, C₁-C₆ alkoxy, C₃-C₈cycloalkyl, C₆-C₁₀ aryl, silyl, substituted silyl, amide, aminoalkyl,alkylamine, alkoxyalkyl, aryloxyalkyl, imidoalkyl, acetylalkyl, hydrogenand halogen (chlorine, bromine, iodine or fluorine).

As a specific example of such tellurium (II) compounds, a synthesis ofN,N′-di-tert-butyl butylenediamide tellurium is a set out belowutilizing a corresponding lithiated precursor and diiodotellurium asreactants, in an ether solvent medium.

The foregoing tellurium precursors have utility in various applicationsfor deposition of Te or Te-containing thin films. Corresponding alkyl,silyl or amide derivatives (wherein chloro substituents are replaced byalkyl or amide functional groups) can also be readily synthesized. Suchalkyl or amide derivatives may be preferred in some thin film depositionapplications, due to their higher volatility properties, in relation tocorresponding chloro compounds having lower volatility as a result oftheir dimeric nature.

The invention therefore contemplates the provision of telluriumcompounds in which the tellurium central metal atom is coordinated withethylenediamine-type ligands, with the tellurium central metal atombeing in a (II) or (IV) state. The invention further contemplatessynthesis of ethylenediamine-type tellurium compounds substituted withalkyl and/or amide substituents. In addition, the invention contemplatesuse of the foregoing tellurium compounds for CVD and ALD applications,to deposit tellurium or tellurium-containing thin films.

In another aspect, the invention relates to dialkyl ditellurides usefulfor CVD and ALD applications carried out at low temperatures to deposittellurium or tellurium-containing films on substrates, e.g., Sb₂Te₃films for the formation of GST films in phase change memoryapplications.

For phase change memory applications, the tellurium precursor employedfor forming GST films desirably has the ability to deposit atsufficiently low temperature to achieve amorphous Sb₂Te₃ films with goodstep coverage, since crystalline films do not provide the necessary stepcoverage for phase change memory device applications. The inventioncontemplates dialkyl ditellurides, e.g., di-tert-butyl ditelluride, toaddress such step coverage issues.

Dialkyl tellurides are conventionally used to deposit tellurium ortellurium-containing films by CVD or ALD in phase change memoryapplications, but relatively high temperatures are needed to depositsuch films. This deficiency can be overcome by use of dialkylditellurides, e.g., di-tert-butyl ditelluride, Te₂(t-Bu)₂.

The reason for the lower deposition temperature achievable by this classof precursors is a relatively weak tellurium-tellurium bond. Anexamination of the X-ray crystal structure of Te₂(t-Bu)₂ reveals afairly long Te—Te bond of 2.68 A. The lower deposition temperature isalso evident from the simultaneous thermal analysis (STA) of Te₂(t-Bu)₂,which shows a very low T50 of 146° C. Te₂(t-Bu)₂ and its synthesis aredescribed in the literature (see, for example, C. H. W. Jones, R. D.Sharma, J. of Organomet. Chem. 1983, 255, 61-70, and R. W. Gedridge Jr.,K. T. Higa, R. A. Nissan, Organometallics 1991, 10, 286-291, and U.S.Pat. No. 5,166,428).

The invention therefore contemplates the use of these dialkylditellurides, e.g., Te₂(t-Bu)₂, as precursors for the deposition oftellurium or tellurium-containing films on substrates, using CVD or ALDtechniques, in applications such as the manufacture of phase changememory devices.

FIG. 5 is an ORTEP diagram of the structure of Te₂(t-Bu)₂.

FIG. 6 is a simultaneous thermal analysis (STA) plot of thermogravimetry(TG) and differential scanning calorimetry (DSC) data for Te₂(t-Bu)₂.

In general, the alkyl moieties of the dialkyl ditelluride compounds ofthe invention can be of any suitable type, e.g., C₁-C₈ alkylsubstituents. Examples include methyl, ethyl, isopropyl, and t-butyl.Preferably, such alkyl substituents include tertiary carbon moieties.Tertiary butyl or tertiary carbons in general are preferred as havinghigh radical stability.

Illustrative examples of dialkyl ditelluride compounds of the inventioninclude dimethyl ditelluride, diethyl ditelluride, diisopropylditelluride, and di-tertiary-butyl ditelluride.

Other ditelluride compounds contemplated by the invention can utilizeother ligands, such as C₁-C₁₂ hydrocarbyl (aryl, fluoroalkyl, allyl,alkenyl, dienyl), or silyl or substituted silyl ligands.

The above-described tellurium precursor compounds of the invention canbe used for chemical vapor deposition and/or atomic layer deposition, toform tellurium or tellurium-containing films on substrates, e.g.,semiconductor wafers or other microelectronic device base structures.Such precursor compounds when present in solid phase can be delivered bysolid delivery techniques, wherein the solid precursor is contained in aprecursor storage and vapor delivery vessel, which is subjected toheating to volatilize the solid precursor, e.g., by sublimation, so thatthe precursor vapor can be discharged selectively from the vessel, asneeded in the downstream deposition process.

The precursor when present in solid phase may also be dissolved insolvent medium, as described above, and delivered by liquid deliverytechniques to a vaporizer, for volatilization to form a precursor vaporthat then is contacted under a vapor deposition conditions with a waferor other suitable substrate. When present in liquid phase, the telluriumprecursor can be delivered by liquid delivery techniques from a suitableprecursor storage vessel. Bubbler techniques may also be employed.

The specific delivery technique employed in the practice of theinvention utilizing such Te(II) and Te(IV) compounds can be selectedbased on the process conditions needed for delivery for contacting withthe substrate on which Te or Te-containing films are to be formed. Ingeneral, it is desired to carry out deposition by CVD and/or ALDtechniques at temperatures below 400° C.

The deposition of tellurium species in accordance with the invention canbe carried out to form GST phase change memory devices, or othertellurium-based microelectronic device structures.

The features and advantages of the invention are more fully shown by thefollowing non-limiting examples.

Example 1 Synthesis of Te[N(SiMe₃)₂]₂

4.78 g (12.53 mmol) of TeI_(e) are suspended in 100 mL of THF in a 200mL Schlenk flask equipped with a magnetic stirring bar. A solution of5.00 g (25.06 mmol) of K[N(SiMe₃)₂] in 50 mL of THF is prepared in a 100mL Schlenk flask. The K[N(SiMe₃)₂] solution is added to the TeI₂suspension via cannula at 0° C. (with ice-bath cooling). The reactionmixture turns yellow immediately and then brown after ca. 10 minutes. Itis stirred another hour at 0° C. and then at ambient temperatureovernight. The volatiles are removed in vacuum and the remaining darkbrown solid is extracted with 100 mL of n-pentane. It is filteredthrough a medium glass-filter frit resulting in an orange solution. Thepentane is removed in vacuum leaving 4.41 g of the crude product behindas an orange solid. The solid is sublimed at 200 mTorr and an oil bathtemperature of 100° C. for two hours, affording 3.37 g (7.51 mmol; 60%yield) of analytical pure product as a yellow, crystalline solid.

The product yielded by the foregoing procedure had the followingcharacteristics: 1H NMR in C₆D₆, ppm: 0.338 (s, 18H, SiMe₃); meltingpoint: 66° C. FIG. 7 is a STA plot of the Te[N(SiMe₃)₂]₂ product.

Example 2 Synthesis of NHTeCl₂

5.00 g (18.56 mmol) of TeCl₄ are suspended in 400 mL of THF (onlypartially soluble) in a 500 mL Schlenk flask equipped with a magneticstirring bar. A solution of 6.40 g (37.12 mmol) ofN,N′-di-tert-butylethylenediamine and 7.51 g (74.24 mmol) oftriethylamine in 10 mL of THF is prepared. This solution in added to theTeCl₄ suspension and the reaction mixture turns cloudy immediately. Amild exothermic reaction is observed. The reaction mixture is stirredovernight a room temperature, and then filtered through a mediumglass-filter frit, leading to yellow solution. The volatiles are removedin a vacuum leaving 5.96 g (16.20 mmol; 87.1% yield) of analyticallypure product behind as a pale yellow, microcrystalline solid.

X-ray analysis quality crystals were obtained by dissolving 0.5 g ofproduct in 6 mL of toluene in a sample vial inside a controlledatmosphere glove-box. The solution is filtered through a PTFE syringefilter and then placed in a −25° C. freezer. After 16 hours large, paleyellow, plate like crystals of the title compound were obtained, whichwere suitable for X-ray analysis.

The compound can be further purified by sublimation. In a typicalexperiment a sublimation device is charged with 5 g of material and thematerial is sublimed at 200 mTorr pressure and an oil bath temperatureof 70° C. for two hours. Typical yields of the sublimation vary between80-90%. The product yielded by the foregoing procedure had the followingcharacteristics: 1H NMR in C₆D₆, ppm: 3.133 (s, 4H, N—CH₂—CH₂—N); 1.189(s, 18H, N-t-Bu).

Example 3 Synthesis of Te[N(SiMe₃)(t-Bu)]₂

3.00 g of (7.87 mmol) TeI₂ are suspended in 100 mL of diethyl ether in a200 mL Schlenk flask equipped with a magnetic stirring bar. A solutionof 2.38 g (15.73 mmol) of Li[N(SiMe₃)(t-Bu)] in 50 mL of diethyl etheris prepared in a 100 mL Schlenk flask. The Li[N(SiMe₃)(t-Bu)] solutionis added to the TeI₂ suspension via cannula at 0° C. (ice-bath cooling).It is stirred another hour at 0° C. and then at ambient temperatureovernight. The volatiles are removed in vacuum and the remaining darkbrown solid is extracted with 150 mL of n-pentane and filtered through amedium glass-filter frit, resulting in an orange solution. The pentaneis removed in vacuum leaving 2.60 g (6.25 mmol; 79.5%) of analyticallypure product behind as a yellow-orange solid. The compound can befurther purified by sublimation at 200 mTorr and an oil bath temperatureof 100° C. for two hours, affording 2.05 g (4.93 mmol; 63% yield) ofproduct as a yellow, crystalline solid. The product yielded by theforegoing procedure had the following characteristics: 1H NMR in C₆D₆,ppm: 1.400 (s, 9H, t-Bu); 0.399 (s, 9H, SiMe₃); melting point: 77° C.FIG. 8 is a STA plot of the Te[N(SiMe₃)(t-Bu)]₂ product.

Example 4 Synthesis of N,N′-di-tert-butyl-2,3-dimethylethylendiamidetelluriumdichloride

2.36 g (8.79 mmol) of TeCl₄ are suspended in 100 mL of THF (onlypartially soluble) in a 200 mL Schlenk flask equipped with a magneticstiffing bar. A solution of 1.77 g (8.79 mmol) ofN,N′-di-tert-butyl-2,3-dimethylethylenediamine and 1.78 g (17.58 mmol)of triethylamine in 5 mL of THF is prepared. This solution in added tothe TeCl₄ suspension and the reaction mixture turns cloudy immediately.A mild exothermic reaction is observed. It is stirred overnight a roomtemperature. The reaction mixture is filtered through a mediumglass-filter frit leading to an amber colored solution. The volatilesare removed in a vacuum leaving 1.93 g (4.85 mmol; 55% yield) ofanalytically pure product behind as an amber colored, microcrystallinesolid.

X-ray analysis quality crystals were obtained by dissolving 0.5 g ofproduct in 5 mL of toluene in a sample vial inside a controlledatmosphere glove-box. The solution is filtered through a PTFE syringefilter and then placed in a −25° C. freezer. After 32 hours pale yellowcrystals of the title compound were obtained, that were suitable forX-ray analysis. The product yielded by the foregoing procedure had thefollowing characteristics: 1H NMR in C₆D₆, ppm: 2.722 (q, 2H,N(Me)-CH—CH-(Me)N); 1.227 (s, 18H, N-t-Bu); 1.080 (s, 3H,N(Me)-CH—CH-(Me)N); 1.059 (s, 3H, N(Me)-CH—CH-(Me)N).

Example 5

Di-tert-butyltelluride and Ge[Pr^(i)NC(n-Bu)NPr¹]₂, wherein Pr^(i) isisopropyl, were utilized as respective tellurium and germaniumprecursors to form a GeTe film. GeTe films can be formed using thisgermanium precursor, denoted GeBAMDN or GeM for ease of notation, anddi-tert-butyltelluride, at temperatures below 300° C. or lower, e.g.,below 280° C. or even 260° C. or lower. In general, lower temperatureswill result in lower content of tellurium, but the specific depositionrate of the film will also depend on the germanium and telluriumdelivery rates in the deposition system.

Di-tert-butyltelluride and Ge[Pr^(i)NC(n-Bu)NPr^(i)]₂ were used todeposit GeTe films at the illustrative conditions identified below, withthe following film thickness and tellurium concentration results.

Sam- Temperature, pressure, Flow rates of GeM Film Thickness, ple FilmGrowth Duration and Te(tBu)₂ % Te in film 1 280° C., 8 torr, 8 min20/160 GeM/Te(tBu)2 124 {acute over (Å)}, 7.3% Te μmole/min 2 260° C., 8torr, 16 min 20/160 GeM/Te(tBu)2 179 {acute over (Å)}, 12.5% Teμmole/min

The invention in another aspect involves use of control agents to combatvapor phase pre-reaction of the precursors described herein, thatotherwise causes uneven nucleation on the substrate, longer incubationtimes for deposition reactions, and lower quality product films. Suchpre-reaction may for example be particularly problematic in applicationsinvolving chalcogenide films, related source materials (O, S, Se, Te,Ge, Sb, Bi, etc.), and/or manufacture of phase change memory andthermoelectric devices.

Pre-reaction may occur when the precursor reagents described herein areintroduced to the deposition chamber, as in chemical vapor deposition,and may also occur in atomic layer deposition (ALD) processes, dependingon the specific arrangement of ALD cycle steps and the specific reagentsinvolved.

The invention therefore contemplates the use of control agents with theprecursors described herein, whereby detrimental gas phase pre-reactionsare suppressed, mitigated or eliminated, so that deposition reactionsare induced/enhanced on the substrate surface, and films of superiorcharacter are efficiently formed.

The control agents that can be utilized with precursors of the inventionfor such purpose include agents selected from the group consisting of(i) heteroatom (O, N, S) organo Lewis base compounds, (ii) free radicalinhibitors, and (iii) deuterium-containing reagents.

These agents can be utilized to lessen deleterious gas phasepre-reaction I′ ll precursors by various approaches, including:

(1) addition to the precursor composition of a pre-reaction suppressantcomprising one or more heteroatom (O, N, S) organo Lewis base compoundssuch as 1,4-dioxane, thioxane, ethers, polyethers, triethylamine (TEA),triazine, diamines, N,N,N′,N′-tetramethylethylenediamine,N,N,N′-trimethylethylenediamine, amines, imines, and pyridine;

(2) addition to the precursor composition of a free radical inhibitor,such as butylated hydroxy toluene (BHT), hydroquinone, butylated hydroanisole (BHA), diphenylamine, ethyl vanillin, etc.;

(3) use of modified chalcogenide precursors, in which hydrogensubstituents have been replaced with deuterium (D) substituents, toprovide deuterated analogs for vapor phase deposition; and

(4) addition to the precursor composition of a deuterium source, todeuterate the precursor in situ.

The pre-reaction-combating agents described above (suppressants, freeradical inhibitors, deuterium sources and/or deuterated precursors) canbe introduced to any of the feed streams to the vapor deposition processin which the film is to be formed. For example, suchpre-reaction-combating agents can be introduced to one or more ofprecursor feed stream(s), inert carrier gas stream(s) to whichchalcogenide precursor(s) or other reagents are subsequently added forflow to the deposition chamber, co-reactant feed stream(s) flowed to thedeposition chamber, and/or any other stream(s) that is/are flowed to thedeposition chamber and in which the pre-reaction-combating agent(s)is/are useful for reduction or elimination of premature reaction of theprecursors that would otherwise occur in the absence of such agent(s).

The aforementioned suppressants, free radical inhibitors and/ordeuterium source reagents in specific embodiments are co-injected withthe precursor(s), e.g., metal source reagent(s), to effect at leastpartial reduction of pre-reaction involving the precursor(s) andreagent(s).

The pre-reaction-combatting agent can alternatively be added directed tothe deposition locus, e.g., the deposition chamber to which theprecursor vapor is introduced for contacting with the substrate todeposit the film thereon, to suppress deleterious vapor phasepre-reaction involving the precursor(s) and/or other reagents.

As another approach, in the broad practice of the present invention, thesuppressant, free radical inhibitor and/or deuterium source can be addedto a solution containing the precursor and/or another metal sourcereagent, and the resulting solution can be utilized for liquid deliveryprocessing, in which the solution is flowed to a vaporizer to form asource vapor for contacting with the substrate to deposit the depositionspecies thereon.

Alternatively, if the precursor and/or another metal source reagent arenot in an existing solution, the suppressant, free radical inhibitorand/or deuterium source can be added to form a mixture or a solutionwith the precursor and/or another metal source reagent, depending on therespective phases of the materials involved, and theircompatibility/solubility.

As a still further approach, the suppressant, free radical inhibitorand/or deuterium source can be utilized for surface treatment of thesubstrate prior to contacting of the substrate with the precursor and/orother metal source reagent.

The invention therefore contemplates various vapor depositioncompositions and processes for forming films on substrates, in whichpre-reaction of the precursors is at least partially attenuated by oneor more pre-reaction-combating agents selected from among heteroatom (O,N, S) organo Lewis base compounds, sometimes herein referred to assuppressor agents, free radical inhibitors, and/or deuterium sourcereagents. Use of previously synthesized deuterated precursors ororganometal compounds is also contemplated, as an alternative to in situdeuteration with a deuterium source. By suppressing precursorprereaction with these approaches, product films of superior charactercan be efficiently formed.

The control agent can be used for combating pre-reaction of chalcogenideprecursor in a process in which multiple feed streams are flowed to adeposition locus to form a film on a substrate, wherein at least one ofthe multiple feed streams includes a precursor susceptible topre-reaction adversely affecting the film, in which the method involvesintroducing the control agent to at least one of such multiple feedstreams or supplied materials therefor, or to the deposition locus.

The pre-reaction combating reagent alternatively can be introduced topassivate the surface of a growing chalcogenide film or slow thedeposition rate, followed by reactivation using an alternative precursoror co-reactant (for example H₂, NH₃, plasma, H₂O, hydrogen sulfide,hydrogen selenide, diorganotellurides, diorganosulfides,diorganoselenides, etc.), thereby carrying out passivation/retardationfollowed by reactivation steps, e.g., as an alternating repetitivesequence. Such sequence of passivation/retardation followed byreactivation can be carried out for as many repetitive cycles asdesired, in ALD or ALD-like processes. The steps may be carried out forthe entire deposition operation, or during some initial, intermediate orfinal portion thereof.

The invention therefore contemplates precursor compositions includingthe precursor and the pre-reaction-combating reagent. Within thecategories of pre-reaction-combating reagents previously described,viz., (i) heteroatom (O, N, S) organo Lewis base compounds, (ii) freeradical inhibitors, and (iii) deuterium-containing reagents, suitablepre-reaction-combating reagents for specific applications may be readilydetermined within the skill of the art, based on the disclosure herein.

Heteroatom (O, N, S) organo Lewis base compounds may be of varied type,e.g., containing an oxo (—O—) moiety, a nitrogen ring atom or pendantamino or amide substituent, a sulfur ring atom or pendant sulfide,sulfonate or thio group, as effective to at least partially lessenpre-reaction of the precursor and other organo metal reagents in theprocess system. Illustrative examples of heteroatom (O, N, S) organoLewis base compounds having utility in specific applications of theinvention include, without limitation, 1,4-dioxane, thioxane, ethers,polyethers, triethylamine, triazine, diamines,N,N,N′,N′-tetramethylethylenediamine, N,N,N′-trimethylethylenediamine,amines, imines, pyridine, and the like.

The heteroatom organo Lewis base compound in various specificembodiments of the invention may include a guanidinate compound, e.g.,(Me₂N)₂C═NH.

One preferred class of heteroatom organo Lewis base compounds for suchpurpose includes R₃N, R₂NH, RNH₂, R₂N(CH₂)_(x)NR₂, R₂NH(CH₂)_(x)NR₂,R₂N(CR₂)_(x)NR₂, and cyclic amines —N(CH₂)_(x)—, imidazole, thiophene,pyrrole, thiazole, urea, oxazine, pyran, furan, indole, triazole,triazine, thiazoline, oxazole, dithiane, trithiane, crown ethers,1,4,7-triazacyclononane, 1,5,9-triazacyclododecane, cyclen, succinamide,and substituted derivatives of the foregoing, wherein R can be hydrogenor any suitable organo moieties, e.g., hydrogen, C₁-C₈ alkyl, C₁-C₈alkoxy, C₁-C₈ alkene, C₁-C₈ alkyne, and C₁-C₈ carboxyl, and wherein x isan integer having a value of from 1 to 6.

The heteroatom organo Lewis base compounds may be utilized in theprecursor composition at any suitable concentration, as may beempirically determined by successive deposition runs in which theheteroatom organo Lewis base compound concentration is varied, andcharacter of the resulting film is assessed, to determine an appropriateconcentration. In various embodiments, the heteroatom organo Lewis basecompound may be utilized in the concentration of 1-300% of the amount ofprecursor. Specific sub-ranges of concentration values within a range of0.01-3 equivalents of the heteroatom organo Lewis base compound may beestablished for specific classes of precursors, without undueexperimentation, based on the disclosure herein.

The pre-reaction-combating reagent may additionally or alternativelycomprise free radical inhibitors that are effective to lessen the extentof pre-reaction between the precursor and another organo metal reagent.Such free radical inhibitors may be of any suitable type, and may forexample include hindered phenols. Illustrative free radical inhibitorsinclude, without limitation, free radical scavengers selected from thegroup consisting of: 2,6-ditert-butyl-4-methyl phenol,2,2,6,6-tetramethyl-1-piperidinyloxy, 2,6-dimethylphenol,2-tert-butyl-4-hydroxyanisole, 3-tert-butyl-4-hydroxyanisole, propylester 3,4,5-trihydroxy-benzoic acid, 2-(1,1-dimethylethyl)-1,4benzenediol, diphenylpicrylhydrazyl, 4-tert-butylcatechol,N-methylaniline, 2,6-dimethylaniline, p-methoxydiphenylamine,diphenylamine, N,N′-diphenyl-p-phenylenediamine, p-hydroxydiphenylamine,phenol, octadecyl-3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate,tetrakis(methylene (3,5-di-tert-butyl-4-hydroxy-hydrocinnamate) methane,phenothiazines, alkylamidonoisoureas, thiodiethylenebis(3,5,-di-tert-butyl-4-hydroxy-hydrocinnamate,1,2,-bis(3,5-di-tert-butyl-4-hydroxyhydrocinnamoyl)hydrazine,tris(2-methyl-4-hydroxy-5-tert-butylphenyl)butane, cyclicneopentanetetrayl bis(octadecyl phosphite),4,4′-thiobis(6-tert-butyl-m-cresol,2,2′-methylenebis(6-tert-butyl-p-cresol), oxalylbis(benzylidenehydrazide) and mixtures thereof. Preferred free radicalinhibitors include BHT, BHA, diphenylamine, ethyl vanillin, and thelike.

Useful concentrations of the free radical inhibitor may be in a range offrom 0.001 to about 0.10% by weight of the weight of the precursor, invarious specific embodiments. More generally, any suitable amount offree radical inhibitor may be employed that is effective to combat thepre-reaction of the precursor in the delivery and deposition operationsinvolved in the film formation process.

The deuterium source compounds afford another approach to suppressingpre-reaction of the chalcogenide precursor. Such deuterium sourcecompounds may be of any suitable type, and may for example includedeuterated pyridine, deuterated pyrimidine, deuterated indole,deuterated imidazole, deuterated amine and amide compounds, deuteratedalkyl reagents, etc., as well as deuterated analogs of the precursorsthat would otherwise be used as containing hydrogen or protonicsubstituents.

Deuterides that may be useful in the general practice of invention aspre-reaction-combating reagents include, without limitation, germaniumand antimony compounds of the formulae R_(x)GeD_(4-x) andR_(x)SbD_(3-x), wherein R can be hydrogen or any suitable organomoieties, e.g., hydrogen, C₁-C₈ alkyl, C₁-C₈ alkoxy, C₁-C₈ alkene, C₁-C₈alkyne, and C₁-C₈ carboxyl, and wherein x is an integer having a valueof from 1 to 6.

The deuterium source reagent may be utilized at any suitableconcentration that is effective to combat pre-reaction of the precursor.Illustrative deuterium source reagent concentrations in specificembodiments of the invention can be in a range of 0.01 to about 5% byweight, based on the weight of precursor.

Thus, a deuterium source compound may be added to one or more of thefeed streams to the vapor deposition process, and/or one of theprecursors or other feed stream components may be deuterated in thefirst instance.

The concentrations of the pre-reaction-combating agents utilized in thepractice of the present invention to at least partially eliminatepre-reaction of the precursors can be widely varied in the generalpractice of the present invention, depending on the temperatures,pressures, flow rates and specific compositions involved. Theabove-described ranges of concentration of the pre-reaction-combatingreagents of the invention therefore are to be appreciated as being of anillustrative character only, with applicable concentrations beingreadily determinable within the skill of the art, based on thedisclosure herein.

The specific mode of introduction or addition of thepre-reaction-combating agent to one or more of the feed streams to thedeposition process may correspondingly be varied, and may for exampleemploy mass flow controllers, flow control valves, metering injectors,or other flow control or modulating components in the flow circuitryjoining the source of the pre-reaction-combating agent with the streamsbeing flowed to the deposition process during normal film-formingoperation. The process system may additionally include analyzers,monitors, controllers, instrumentation, etc., as may be necessary orappropriate to a given implementation of the invention.

In lieu of introduction or addition of the pre-reaction-combating agentto one or more of the flow streams to the vapor deposition process, thepre-reaction-combating agent may be mixed with precursor in the firstinstance, as a starting reagent material for the process. For example,the pre-reaction-combating agent may be mixed in liquid solution withthe precursor, for liquid delivery of the resulting precursor solutionto a vaporizer employed to generate precursor vapor for contact with thesubstrate to deposit the film thereon.

As mentioned, the pre-reaction-combating agent may be added to thedeposition locus to provide active gas-phase suppression of pre-reactionof the precursor vapor(s) that would otherwise be susceptible to suchdeleterious interaction.

As a still further alternative, the pre-reaction-combating agent may beused as a preliminary surface treatment following which the precursorand co-reactants (e.g., H₂, NH₃, plasma, H₂O, hydrogen sulfide, hydrogenselenide, diorganotellurides, diorganosulfides, diorganoselenides, etc.)are delivered to the substrate surface to effect deposition on suchsurface. For such purpose, the pre-reaction-combating agent may beintroduced into one of more of the flow lines to the deposition processand flow to the substrate in the deposition process chamber, prior toinitiation of flow of any precursors. After the requisite period ofcontacting of the substrate with such pre-reaction-combating agent hasbeen completed, the flow of the pre-reaction-combating agent can beterminated, and normal feeding of flow streams to the deposition chambercan be initiated.

It will be apparent from the foregoing description that thepre-reaction-combating agent may be introduced in any of a wide varietyof ways to effect diminution of the pre-reaction of the precursor in thedeposition system.

In one embodiment of the invention, a vapor phase deposition system iscontemplated, comprising:

a vapor deposition chamber adapted to hold at least one substrate fordeposition of a film thereon;

chemical reagent supply vessels containing reagents for forming thefilm;

first flow circuitry arranged to deliver said reagents from saidchemical reagent supply vessels to the vapor deposition chamber;

a pre-reaction-combating agent supply vessel containing apre-reaction-combating agent;

second flow circuitry arranged to deliver the pre-reaction-combatingagent from the pre-reaction-combating agent supply vessel to the firstflow circuitry, to said chemical reagent supply vessels and/or to thevapor deposition chamber.

FIG. 9 is a schematic representation of a vapor deposition system 100 inone embodiment thereof.

In this illustrative system, a pre-reaction-combating agent is containedin a supply vessel 110. The pre-reaction-combating agent can comprise apre-reaction suppressant, a free radical inhibitor, a deuterium source,or a combination of two or more of such agents and/or types of suchagents.

The pre-reaction-combating agent supply vessel is joined by respectiveflow lines 112, 114 and 116, to germanium, antimony and telluriumreagent supply vessels, labeled “G,” “S” and “T,” respectively. Thegermanium precursor in vessel “G” may be a tetraalkyl or tetraamidogermanium compound, such as tetramethyl germanium, tetraethyl germanium,tetraallyl germanium, tetrakis(dimethylamino)germane or other organogermanium compounds. Furthermore, precursor “G” may be a germylenecompound wherein the lone pair on Ge(II) can react in the gas-phase withchalcogen precursors in the absence of a pre-reaction suppresant. Theantimony precursor in vessel “S” can be a trialkyl or triamido antimonycompound, such as tributyl antimony, triisopropyl antimony,tris(dimethylamino)antimony or other organo antimony compound. Thetellurium precursor in vessel “T” can be a dialkyl or diamido telluriumcompound, such as diisopropyl tellurium, dibutyl tellurium,bis[bis(trimethylsilyl)amino]tellurium or other organo telluriumcompound.

The pre-reaction-combating agent therefore can be added to any of thegermanium, antimony and/or tellurium precursors in the respective “G,”“S” and “T” vessels, via the corresponding flow line(s), which for suchpurpose may have flow control valves or other flow-modulating componentstherein.

In the specific process embodiment shown, the germanium, antimony andtellurium precursors are flowed in liquid form in feed lines 118, 120and 122, respectively, to the mixing chamber 124, and the resultingprecursor mixture then is flowed from the mixing chamber 124 in line 126to vaporizer 128. In the vaporizer, the liquid precursor mixture andpre-reaction-combating agent are volatilized to form a precursor vapor.The precursor vapor then flows in line 130 to the showerhead disperser134 in vapor deposition chamber 132, for discharge of precursor mixtureonto the wafer substrate 136 mounted on susceptor 138 in the depositionchamber.

The precursor vapor contacting the wafer substrate 136 serves to depositthe germanium, antimony and tellurium metals on the substrate, to form athin film of germanium-antimony-tellurium (GST) material, e.g., formanufacture of a phase change random access memory device.

The contacted precursor vapor, depleted in metals content, is dischargedfrom the vapor deposition chamber 132 in line 140, and flows to theeffluent abatement unit 142. In the effluent abatement unit 142, thedischarged effluent vapor is treated, e.g., by scrubbing, catalyticoxidation, electrochemical treatment, or in other manner, to yield afinal effluent that is discharged from the abatement unit in line 146.

It will be appreciated that these schematic representation of the vapordeposition system shown in FIG. 9 is of an illustrative character, andthat numerous other arrangements could be utilized for deployment anduse of the pre-reaction-combating agent, including those previouslyillustratively discussed herein. For example, the pre-reaction-combatingagent could be introduced directly to the mixing chamber 124, forblending therein with the respective GST precursors. Alternatively, thepre-reaction-combating agent could be introduced into manifold 118, orother mixing chamber, blender, etc., for combination with the precursorthat is being transported to the deposition locus.

The system shown in FIG. 9 employs liquid delivery of the respectiveprecursors. It will be recognized that if solid-phased precursors areemployed, then solid delivery techniques may be employed, in which solidprecursor is volatilized, e.g., by sublimation of the solid startingmaterial.

In lieu of using a deuterating agent as the pre-reaction-combating agentin the FIG. 9 system, one or more of the germanium, antimony andtellurium precursors could be supplied in the first instance as adeuterated analog of an organo germanium, antimony or telluriumprecursor, in which hydrogen substituents of the organo moiety have beenreplaced with deuterium.

The pre-reaction-combating reagents may be employed in the broadpractice of the present invention to produce improved films for themanufacture of semiconductor products. In general, thepre-reaction-combating reagents described herein may be utilized invarious combinations in specific applications, to suppress or eliminatepre-reaction of the precursor(s) and provide superior nucleation andfinal film properties.

While the invention has been described herein in reference to specificaspects, features and illustrative embodiments of the invention, it willbe appreciated that the utility of the invention is not thus limited,but rather extends to and encompasses numerous other variations,modifications and alternative embodiments, as will suggest themselves tothose of ordinary skill in the field of the present invention, based onthe disclosure herein. Correspondingly, the invention as hereinafterclaimed is intended to be broadly construed and interpreted, asincluding all such variations, modifications and alternativeembodiments, within its spirit and scope.

What is claimed is:
 1. A method of forming a phase change materialcomprising a tellurium-containing film, comprising volatilizing atellurium precursor composition to form a tellurium precursor vapor, andcontacting the tellurium precursor vapor with a substrate to deposittellurium thereon, wherein the tellurium precursor composition comprisesa tellurium precursor comprising Te₂(t-Bu)₂ wherein t-Bu is tertiarybutyl.
 2. The method of claim 1, wherein the phase change material is aGST film.
 3. The method of claim 1, wherein the contacting comprisesatomic layer deposition.
 4. The method of claim 1, wherein thecontacting comprises chemical vapor deposition.
 5. The method of claim1, wherein the tellurium-containing film is an amorphous Sb₂Te₃ film. 6.The method of claim 1, wherein the tellurium is deposited at atemperature below 300° C.
 7. A method of forming a GST film comprisingvolatilizing a tellurium precursor composition to form a telluriumprecursor vapor, and contacting the tellurium precursor vapor with asubstrate to deposit tellurium thereon, wherein the tellurium precursorcomposition comprises a tellurium precursor comprising Te₂(t-Bu)₂wherein t-Bu is tertiary butyl.
 8. The method of claim 7, wherein thecontacting comprises atomic layer deposition.
 9. The method of claim 7,wherein the contacting comprises chemical vapor deposition.
 10. Themethod of claim 7, wherein the tellurium is deposited at a temperaturebelow 300° C.